Johannesburg: South African police officers killed more than 30 striking workers at a Lonmin PLC platinum mine who charged a line of officers trying to disperse them, authorities said on Friday.

The shooting on Thursday is one of the worst in South Africa since the end of the apartheid era.

Police ministry spokesman Zweli Mnisi said on Friday that more than 30 people were killed. He said an investigation into the shooting near Marikana, about 70 kilometers northwest of Johannesburg was underway.

The shooting happened on Thursday afternoon after police failed to get the striking miners to hand over machetes, clubs and other weapons.

Some miners did leave, though others carrying weapons began war chants and soon started marching toward the township near the mine, said Molaole Montsho, a journalist with the South African Press Association who was at the scene.

The police opened up with a water cannon first, then used stun grenades and tear gas to try and break up the crowd, Montsho said. Suddenly, a group of miners rushed through the underbrush and tear gas at a line of police officers. Officers immediately opened fire, with miners falling to the ground.

Dozens of shots were fired by police armed with automatic rifles and pistols. Images broadcast by private television station e.tv carried the sound of a barrage of automatic gunfire that ended with police officers shouting, "Cease fire!" By that time, bodies were lying in the dust, some pouring blood. Another image showed some miners, their eyes wide, looking in the distance at heavily armed police officers in riot gear.

It was an astonishing development in a country that has been a model of stability since racist white rule ended with South Africa's first all-race elections in 1994. The shooting recalled images of white police firing at anti-apartheid protesters in the 1960s and 1970s, but in this case it was mostly black police firing at black mine workers.

It remains unclear what sparked the miners' fatal charge at police. Mnisi, the police ministry spokesman, claimed the miners shot at police as well, using one of the weapons they stole from officers on Monday.

"We had a situation where people who were armed to the teeth, attack and killed others even police officers," the spokesman said in a statement on Thursday night. "What should police do in such situations when clearly what they are face with are armed and hardcore criminals who murder police?"

President Jacob Zuma said he was "shocked and dismayed at this senseless violence."